Yes, FTP is known to be problematic right now. We are still working on the correction. Follow the post you mention for updates (https://biostar.usegalaxy.org/p/24618/ ). This is a priority correction and we expect it to be resolved soon.

Files still must be < 2 GB to use the "browser upload" method. To load larger files right now, or if browser upload is slow for even smaller data, one workaround is to place the data in a publically accessible location and load via URL. Upload options FAQ

Thanks for reporting the issue. Your description is exactly how the service is currently failing in our internal tests as well.